(1) Field of the Invention
The present invention relates generally to convection baking ovens, and more specifically, to an improved convection baking oven having at least one row of vertically arranged air outlets and an air flow control system.
(2) Description of the Prior Art
Rack ovens are chamber-type ovens in which the bakery products are supported on pans or other carriers in a rack. The rack is usually provided with wheels and can be moved into the oven chamber when loaded with the bakery products and moved from the oven chamber when the baking is completed.
In the past, various devices have been employed to conduct heated air over the bakery products being baked in the oven. Most of those devices have required various arrangements to move the bakery product or the supporting racks in order to provide even distribution and contact with the heated air passing through the oven.
The reason it has been necessary in the past to provide some kind of device in commercial ovens to cause movement of the bakery products within the oven baking chamber is to insure that the product will move through the variable heat zones for uniform distribution and for even baking or processing. In contrast, small home use ovens have such a limited volume that it is not necessary to move the product around in the oven to achieve satisfactory baking.
In addition to moving the rack, other arrangements have been utilized to provide for even flow across the baked goods. One type of oven popular for baking is an oven in which a portion of the flue gases from a firebox located under the baking chamber enters a plurality of ports going from near the top of to near the bottom of the oven chamber to cause a downwardly directed current of heated air to thereby mix and circulate the gaseous contents of the oven chamber and prevent it from separating into different layers and pockets of different temperatures. However, such an arrangement would not be adaptable to rack ovens in which the oven chamber is even with the floor of the bakeshop.
Another type is an oven in which a control means delivers various amounts of heated air through an alternating pattern of jet orifices on opposite sides of the oven. Hot air from the jets on the opposite sides of the oven meet in an area of common velocity in the chamber to produce turbulent mixing of the hot air in a vertical plane. The air pressure is varied between the hot air jets and the opposite side walls to cause the vertical plane of turbulent heat air to sweep back and forth through the chamber, thereby contacting the entire product. However, like the other prior art bakery ovens, this arrangement requires additional moving parts in order to continuously vary the air pressure.
In addition, bakers sometimes use an oven having a baking chamber in which air channels on both sides are provided with warm air by a blower through a series of small slots, which extend over the depth of baking chamber. The heated air introduced into the oven is returned to the blower by means of an air passage opening in the adjacent wall. However, such an arrangement is complex, bulky and expensive to construct.
One approach to trying to solve these problems is disclosed in U.S. Pat. No. 5,228,385, issued Jul. 20, 1993, and commonly owned by Applicant. This convection oven included a fan located in the top of the oven for circulating heated air in a closed path through the interior of the oven and a plenum located in the pair of opposed sidewalls adjacent to the sidewall having the opening. The plenum extended substantially from the top to the floor of each sidewall and included a plurality of horizontal air outlet slots extending substantially the depth of the oven. The horizontal air outlet slots were arranged with a 1:1 correspondence with respect to each rack of the multilayer wheeled cart. Heat recovery means was located in the plenum portion of the opposed sidewalls and an inlet was located in the top of the oven adjacent to the fan for receiving the air after it has passed through the interior of the oven and returning the air to the inlet of the fan. However, even this type of oven could not produce baked goods having the near perfect uniformity associated with continuous type ovens.
Thus, there remains a need for a new and improved batch-type convection baking oven which provides at least one row of vertically arranged air outlets for even baking of the bakery goods in the rack while, at the same time, includes an air flow control system which is simple to construct and maintain.